The present study examines the unity in the sociolinguistic diversity of the European Union. The European languages are presented as among the few common European achievements which have been fulfilling their European functions for a long time. The latter today constitute the foundation of the sociolinguistic structure of the European Union. In that structure, the languages are changing their original sociolinguistic functions and the language communication in uniting Europe attains new sociolinguistic dimensions which specificity and regional originality fill with meaning and contents the terms “Euroglossia” and “Eurolingualism”, coined to reflect the unity in the sociolinguistic diversity of the linguistic regime of the European Union. The book is intended for specialists in the sphere of sociolinguistics, sociology of language, general and applied linguistics, for psychologists, anthropologists, political and cultural scientists who work in the sphere of European integration, language policy and linguistic human rights protection, but also for a broader circle of readers who are interested in the social being of European languages.